Induction electric furnace.



w. s. MOODY. INDUCTION ELECTRIC FURNACE.

APPLICATION FILED OCT. 18, 1906. I I

- Patented 0ct..6, 1914.

ZSHEETS-SHEBT /nvemiorx Wa/erS/Waoay Witnesses:

K/IZM/ W. S. MOODY. INDUCTION ELECTRIC FURNACE.

APPLICATION FILED OUT. 18, 1906.

Patented Oct. 6, 1914 2 SHBETSHEET 2 material, it.

nace.

" I melting metals,

1 than is charge of metal, each its proportional part jadjacentpart of the secondary (the charge) but'if-the crucible should be but half full. it

" and outer parts UNITED STATES PATENT WALTER sMoomr, or SCHENECIADY,

OFFICE.

NEW YORK, ASSIGNOR- TO GENERAL ELECTRIC COMPANY, A CORPORATION OF YORK.

INDUCTION ELECTR-IC FURNACE.

Specification of Letters Patent.

Patented Oct. 6, 1914.

Application filed October is, 19pm seria no. 339,481.

specification.

This invention relates to apparatus for smelting ores and similar operations, in which an electric current sufficient to cause a melting heat is induced in the material under treatment. To effect this, said material is placed in an annular crucible and arranged to constitute the closed secondary of a transformer, Whose primary is arranged concentric with said crucible. A suitable. fcore passes centrally through the crucible. In furnaces of this character which have been heretofore pros posed, the primary coil has been a single element, arranged either wholly outside of the crucible or wholly inside the same. Inasmuch as the walls of the crucible must be of considerable thickness, to give them strength enough to safely hold the charge of melted follows that the distance between ;the primarv coil and the charge, which forms the secondary coil, is greater usual in ordinary transformers. The reactance of the furnace is therefore excessive, and increases with-the size of the fur- Ina furnace of thiskind if the ancrucible is completely filled with'a primary turn induces of the current in the nular is evident that'theprimary turns near the top .h-aveno corresponding secondary, and thereforethe reactance between these turns and the charge located in the lower part of the furnace must be high. Moreover, the reactance between the charge and the'inner of the Winding is not equal. For purposes of economy, it is desirable to use a high frequency generator. In order, therefore, to enable a higher frequency tobe employed to treat a given load, it is necesance if a reasonably high power factor is to bemaintaified. I find that I can make a large induction erated satisfactorily with commercial frequencies by subdividing the primary coil,

1 one part being placed inside the following is a' avoided, Theoretically,

way to reduce the react- I furnace which can be pcool.

the crucible and the other; part out-side. Moreover, by making each part in superposed sections, and connecting all the sections in multiple. the load on the primary will be taken by those SECUODS in the plane of the charge, and the excessive reaotance above mentioned will be the perfect a1"- rangementwould be to have every turn in multiple with every other turn, but since this is practically impossible, the winding is divided into number of sectionshe accompanying drawing shows an ina reasonable duction furnace embodying my improved construction.

Figure l is a vertical diametrical section on line 1, 1, F1g.

2; Fig. 2 is a plan View; Fig. 3 is a diagram of the primary winding; and Fig.4 is a. perspective view of a piece of said winding.

The crucible l is composed of refractorymaterial, such as firebrick, and is annular in shape". It is supported on a suitable foundation 2, and 1s provider with a top plate 2; and a removable cover 3 of fire clay or the like,

made in segments. 'A spout 4 is located at some convenient point below the level of the charge in the crucible, hole, closed by a plug 5, connects -the crus cible with said spout for drawing off the molten metal. The thickness'of the, walls of the 'crucible is no greater than is neccs sary to hold the charge 6 safely, in order that the primary coils may come as near to the charge as possible. The charge constitutes a short ci rcuited secondary coil, and is readily melted by the heat generated there in when an alternating current. flows through the primary winding.

1 One leg 7 of a laminated core of the core type passes centrally through the annular crucible, the other leg or legs 8 being outside thereof. Aspaceis left between the central leg 7 and the crucible in which is wound a suitable length of copper-conductor, prefera'bly'a copper tube 9, having the turns 'insulated from cache-ther' and from the core.

similar coil 10 is wound around the outside of the crucible,

and the two tubes are coupled together at 11, Figs. 2 and-3 so as to. constitute. one continuous tube. At 12 are connections whereby a supply of water can be circulated through the tube to keep it The electric current from the mains and a tap each part of g Q 1,113,1auiv 13' flows through the. walls of the copper part being composed of sections connected tube, or if desired, a stranded cable 14, as in multiple. l shown in Fig. 4, may be provided inside the '7. An electriclfurnace comprlsing an antube to carry some of the current 'and there- -nular crucible, a core; passing centrally by allowing a thinner tube to be used to, through the same, and a primary winding lessen the eddy losses. divided into two parts, one .inslde of said Bot'lr-t-he inner andthe outer coils are dicrucible and the other outside thereof, each 2 vided into superposed sections, separated, if part being composed of sections connected in desired, by an insulating diaphragm 15. In multiple and superposed. v

10 the present instance, eachcoil is divided into- 8. An electric furnace of the induction two sections, and the four sections are all type comprising a primary winding con,- connected in multiple to the mains13. Insisting of a metallic tube with a metallic 75 sul'ating couplings *16 are used to breakfthe conductor passing: through the same.

. tube into electrically separate portions, and 9. An electric furnace of the induction the'jcable It also must be similarly intertypecomprising a primary Winding conruptedc n iilently with the joints in the sisting of a metallic tube with'a stranded pipe. The connections with the mains-13 metallic conductor passing, through the so are made by branch conductors 17 attached e, f l

to the tube at each side of thec up ngs, a 10. An electric furnace. of the induction 20shown in Fig. 3. The outer sectionsmay t e jsin a p i aiy winding conhave a smaller cross-section than the inner igti g f ti u u t lli t b 1' because they take l s current. n the vided into electrically independentsections, 85 her, due to the fact that the mutual reactand insulating coupl' gs between aid ance between them and the-secondary is li 2 greater than that between the inner sections 11. electric furnace of the induction and the secondary. v type'comprising an annular crucible, and a Wh t'I'c m as e anddeslre 9 primary winding divided into tw'o' parts, 90 by Letters Patent of the United States, one inside and the other outside of said ILAn electric furnace comprising a cruclcrucible, the outer part being 1 smaller in 3 1 a 0 pas g through fi cross-section than the inner, and said parts and a primary windin' divided into two b in connected i lti l parts connectedin mnltlpl Wi h each O 12. An electric furnace of the induction 95 one inside of said-crucible and the other. ty comprising'a crucible, a core, and-a; a outside thereof. primary winding formed of a plurality of 2.'An electric furnace comprising an ansections connected in multiple with each n arcrucible, a core passing centrally other and inductively related to'sai'd crucithrough vsaid crucible, and a primary windbl g'di d OtWO parts, one inside of said 13. An exciting winding consisting of seccrucible 'and the. ctheroutside thereof, said ti f tubing electrically c0nnected;"ig1' 40 winding consisting f hin PPB b ng multiple with each other, and means for suitably insulated. passing a cooling fluid successively through 3. Anelectric furnace comprising a magid cti I a 1- netic core, a primary winding surrounding 14. The combination of a plurality of secone-leg ofsaid core and divided into two tions of tubing connected together by elecconcentric coils connected in multiple with trically insulating joints to form a coneach other, and an annular crucible concentinuous tube, and electrical connections trio with andlocated between said coils. joining said sections in multiple with each 110 4.'An electric furnace'comprising an another.

- nular crucible, a core passing centrally 15. An electric furnace comprising acrucithrough said crucible, and a primary windble, a core, a primary winding formed of a 1 ing concentric with said crucible and diplurality of sections of tubing electrically vided into sections connected in multiple. connected in multiple with each other and 115 5. An electric furnace comprising an anmechanically connected by insulating joints nular crucible, a core passing centrally to form a continuous tube, and means for through said crucible, and a primary windpassing a cooling fluid successively through ing. concentricwith said crucible and dithe sections of tubing. v vided into superposed sections connected in In witness whereof,- I have hereunto set 12 migltiile. 1 fu a my hand this 11th day of October, 1906.

' e ectric rnace comprisin an an- 4 nular crucible, a core passing entrally WALTER SMOODY through the same, and a primary winding .Witnesses: divided into two parts, one inside of said BENJAMIN B. HULL, crucible and the other outside thereof, each HELEN ORFORD. 

